Observations about nature in the city, gardening, craft, and curiosities

Sunday, July 19, 2009

Good Vibrations

My potato plants have blossoms, and I was amazed at what pretty flowers they are. I don't remember potato blossoms in quite this color before. Then, when I went out to photograph them, I discovered a bumblebee busily flitting from blossom to blossom, doing her pollination thing.

I know that bumblebees like this one perform a special service for certain types of plants, called "buzz pollination," but I didn't understand quite what that was until recently, when I interviewed an entomologist for the fall issue of MOQ. I wanted to know more about bumblebees in the city, and specifically what we might look for when observing bees in the fall.

She (Elaine Evans) explained that certain flowers, like potato and tomato blossoms (closely related plants, by the way), have this cone-shaped center that contains the pollen. In order to get the pollen out, bumblebees grab hold of the cone with their mandibles and then vibrate their wing muscles without actually moving their wings, so that their whole body vibrates, and in so doing, manage to shake loose the pollen inside the cone. From the bees' point of view, they get the protein-rich pollen to eat, an important part of their diet. But it has the added benefit, from the plants' perspective, of getting that pollen out and onto parts of the bee's fuzzy body, which provides a way for that pollen to mix with the pollen from other potato blossoms, thus allowing seed formation to happen.

While we humans don't really need this to happen with potatoes, because we eat the roots, not the fruits, for other plants with these pollen cones -- tomatoes being the most notable example -- this is such a valuable service that commercial tomato growers actually purchase or "rent" hives of bumblebees to ensure that their plants get pollinated and they get a good crop as a result.

Honeybees don't perform this particular service -- buzz pollination -- so the peculiar shimmy of the busy bumblebee is especially important to growers of tomatoes and any other plants with their pollen trapped inside these floral cones.

It was fun watching this bumblebee grabbing hold of the cone at the center of the flowers and doing the shimmy, then moving on to the next blossom.